1. Field of the Invention
This invention relates to photographic apparatus and, more particularly, to an improved drive system for advancing and rewinding film in a film cassette inserted into the photographic apparatus.
2. Prior Art
Recent important technological advances have made it possible to provide multi-purpose motion picture cassettes from which the film need not be removed during exposure, processing and projection operations. Exemplary of such systems are those described in U.S. Pat. No. 3,615,127 of Edwin H. Land issued Oct. 26, 1971; and U.S. Pat. No. 3,77,861 of Edwin H. Land issued Nov. 13, 1973.
Such systems utilize replaceable film cassettes, each containing a strip of film, a supply of processing composition for the film, and an internally programmed processor responsive to manipulation of the film in the cassette for applying the processing composition to the film after its exposure. Initially the cassette is inserted into a camera for exposure of the film. After exposure, it is loaded into a projector apparatus which is adapted to receive the cassette and has a drive apparatus for manipulating the film in the cassette. The film is manipulated in a sequence determined by a signal provided by the cassette that indicates whether or not the film has been processed.
When a cassette containing unprocessed film is inserted into the projector, movement of the film activates the processor, developing the film to produce a series of fixed, visible, projectable images as the film is driven by the drive system. Thereafter, the apparatus manipulates the film in an optical system, causing it to be projected for viewing. The film is then rewound from a takeup spool onto a supply spool for storage and subsequent reuse. The speed at which the film is rewound exceeds the speed at which the film is advanced during the projection mode. Finally, the cassette is automatically ejected. In response to insertion of a cassette containing processed film, the apparatus simply projects the film, rewinds it, and then ejects the cassette.